ArcGIS for Server software gives you the ability to create, manage, and distribute GIS services over the Web to support desktop, mobile and Web mapping applications. ArcGIS Server can be deployed on-premise and to private and public clouds such as Amazon EC2.
To create GIS services, you use ArcGIS for Desktop to author geographic content, such as maps and GIS tools, and then publish that content using ArcGIS for Server so that it can be used anywhere in your enterprise and on the Web.
ArcGIS for Server simplifies access to GIS services for GIS professionals, mobile workers, as well as knowledge workers without any GIS experience. With ArcGIS for Server, you stay in control of your content through centralised management of spatial data, including imagery.
In addition, ArcGIS for Server provides you with a scalable GIS server platform that can be deployed on a single machine to support small workgroups, or it can distributed across multiple servers for supporting enterprise applications. You can also deploy ArcGIS for Server on Cloud infrastructure.